Professional whitening does not change the structure of the enamel by thinning it. The active ingredient in whitening gel is hydrogen peroxide, which penetrates the surface and breaks up stains. Some people have more translucent teeth to begin with and whitening may enhance the translucency. In all cases, it is critical to do these procedures under the supervision of a dentist.
Teeth bleaching absolutely does not thin teeth enamel
Absolutely not. Imagine how many times we would be sued if every time we performed teeth whitening the enamel got thinner. Of course, if you use an acidic rinse from over the Internet to whiten your teeth, then yes.
As long as you are using a bleaching system that has the ADA seal of approval, you will not harm the enamel on your teeth. There are some systems "out there" that may have a low pH which would cause damage to enamel.
Some people may have "thinner" and more translucent enamel, which becomes more sensitive with prolonged bleaching. If that is the case, simply bleach at home with professional trays and stop as you feel an incresed sensitivity.
There is virtually no effect to the volume of enamel during the bleaching process. People "addicted" to bleaching (where they constantly bleach) can begin to have transparent enamel and show the underlying dentin, but it is only the appearance that is affected.
The only studies that have been able to show damage to enamel were when extracted teeth were treated in a fashion that is nearly to recreate in real life. If the bleaching is done under the supervision of a dentist,...